1. Field of the Invention
This invention relates to novel method and apparatus for folding metal sheets into box-like structures which can serve for versatile purposes, for instance, as anti-rust top covers for stacked metal sheets to be packed for transportation.
2. Description of the Prior Art
Thin steel sheets products are usually shipped out from a factory in the form of stacks each containing a large number of sheets of a predetermined size. The stacked steel sheets are wrapped in packing paper and then applied, on all sides, with protection covers, including side-protecting iron plates of inversed L-shaped in section, a top-protecting iron plate and a bottom-protecting iron plate, finally binding them together with packing tapes.
The sheet products which have been packed in this manner are stacked on a deck of a freight ship or sometimes stored in open air when suitable storing facilities are not available. In such a case, there has been a serious problem in that splashes of sea waves or rain water get into the packed products through gap between the top- and side-protecting cover plates, producing rust on the sheet products to deteriorate their quality to a considerable degree.
As a measure to prevent such problem, it has been proposed to cover the top of the stacked sheet products with a box-like structure of metal sheet. The box-like cover is formed, for example, by folding four sides of a rectangular steel sheet at right angles as shown in FIG. 1, to form side sections 1 and sections 2. The doubled triangular wedge-like portions 3 at the joints of the adjacent side and end sections 1 and 2 are then lapped onto the outer surfaces of the side section 1 or end section 2 to form a structure as shown in FIG. 2.
However, a box structure of that type which has the wedge-shaped portions 3 simply lapped onto the outer surfaces of the side sections 1 or end sections 2 has a difficulty in that the pointed ends of the wedge-shaped portions 3 have a tendency of disengaging from the outer surfaces of the side sections or end sections, hurting or scratching worker's hands or other things while may touch them. In addition, the wedge-shaped portions which are exposed on the outer surfaces of the side or end sections impair the appearance of the box-like structure itself.